The purpose of the research is to determine the ability to alter movement displacement, velocity, and timing, through the manipulation of speaking rates in patients with neuropathologies at different levels of the central nervous system. Speech rate is manipulated both extrinsically (using timers, and delayed auditory feedback) and intrinsically by patients during imitation of speech tokens. The effects of increasing and decreasing speech rate on speech articulator movement displacement and velocity is being studied to determine whether an optimum speech rate can be found in individual patients and whether this differs according to which CNS structures are involved. Further, the effects of speech rate manipulation on the coordination and pattern of timing between movement onsets and offsets is being examined to determine whether time patterning remains intact in different types of neurologic disease. The purpose is to identify those neurologic structures involved in maintaining time phase relationships between the articulators in speech motor control. The onset and offset of movements of the rib cage, abdomen, lips, jaw and larynx are being studied for change in different rate conditions in the following types of neurologic disease; cerebellar ataxia, dystonia, Parkinson's disease, and Huntington's disease.